The mammalian oocyte, like that of all other organisms, occupies a unique position in the life history of the species, for it is absolutely essential for the continuity of life from one generation to the next. Folliculogenesis is a precise series of developmental events that requires the cooperative efforts of several cell types comprising the Graafian follicle ant the integration and modulation of a complex set of chemical messages that ultimately insure maturation and survival of the oocyte and finally bring about its ovulation. Basic to any attempt to elucidate the integrated functions of the developing Graafian follicle resides in the understanding of the unique structural and physiological features of each component. A defect in one cell type or one component may have marked repercussions on another constituent. The objective of this proposal is to learn some of the basic, fundamental aspects of the dynamic morphology and function of the oocyte and multifunctional granulosa cell as it is related to follicular development under normal and experimental conditions. The specific aims of the proposal are: (A) to determine how to granulosa cell subclasses regulate the fate of the follicle in a reconstituted model system. (B) To determine the effects of stromal tissue on differentiative properties of large and small granulosa cells. (C) To characterize the transformation of granulosa cells during cystogenesis and to evaluate the role of the basement membrane in the process. (D) To characterize macromolecules of the follicular microenvironment in relation to ongoing oogenesis, folliculogenesis or cystogenesis. The proposed experiments will use in vivo and in vitro techniques, bicameral culture system, light and electron microscopy, immunocytochemical methods, radioimmunoassay, colloidal gold-protein A immunocytochemical methods, biochemical techniques, and computer technology. The expected fundamental data will be integrated with that obtained about the reproductive process in general through other biological disciplines.